JP6710068B2 - Pneumatic tire - Google Patents

Description

The present invention relates to a pneumatic tire.

Tire noise generated by a tire rolling during traveling of an automobile is regarded as one of tire performances, and various improvements for improving the tire performance have been studied. One of the factors that cause tire noise is radiated sound due to vibration of the tread portion.
By the way, in recent years, the weight of tires has been reduced in order to reduce the rolling resistance of the tires. With the weight reduction, the damping property of vibration in the rolling tires is reduced, and the radiation noise emitted from the tires is reduced. Tends to be large.
As a means for reducing the radiated sound, for example, a pneumatic tire (see Patent Document 1) has been proposed in which noise performance is improved while maintaining steering stability performance and rolling resistance performance.

International Publication 2013/161296 Publication

Under such circumstances, for example, even when the rolling resistance of the tire is reduced by reducing the weight of the tire and the like, a tire that can more effectively suppress the radiation sound due to the vibration of the tread portion is desired. ing.
Therefore, an object of the present invention is to provide a pneumatic tire that suppresses radiated sound and improves noise performance.

In order to achieve the above object, the pneumatic tire according to the present invention has a carcass that extends in a toroidal shape between a pair of bead portions, and is arranged on the tire radial direction outer side of the crown portion of the carcass and with respect to the tire circumferential direction. A pneumatic tire comprising: a slanted belt including at least two slanted belt layers having slanted cords; and a tread arranged on the outer side in the tire radial direction of the slanted belt layer, wherein the slanted belt is a tire. A tire width direction width of the wide slope belt layer is W1, which is arranged through the equator and is composed of at least a wide slope belt layer having a relatively wide width in the tire width direction and a relatively narrow slope belt layer. The tire width direction width of the narrow slope belt layer is W2, the tire width direction distance from the tire width direction end of the wide slope belt layer to the tire width direction end of the narrow slope belt layer, the longer one is D1, When the shorter one is D2, W2/W1=0.2 to 0.7 and D1/D2=2.0 to 8.0.
According to the pneumatic tire of the present invention, it is possible to suppress radiation noise and improve noise performance.

In the pneumatic tire of the present invention, when the inclination angle of the cord of the wide-width inclined belt layer with respect to the tire circumferential direction is θ1 and the inclination angle of the cord of the narrow-width inclined belt layer with respect to the tire circumferential direction is θ2, 30°≦θ1 It is preferable that ≦85°, 10°≦θ2≦30°, and θ1>θ2. According to this configuration, it is possible to increase the cornering power, realize high turning performance, and reduce the emitted sound.
In the pneumatic tire of the present invention, it is preferable that the vehicle mounting direction is specified such that the side of the tire width direction distances D1 and D2 on which D2 is located is located inside the vehicle mounting direction. According to this configuration, a lateral force is generated from the pair of tires toward the inside in the vehicle mounting direction, and the steering stability (toe-in effect) when traveling straight ahead is improved.

In the present specification, the width in the tire width direction and the like described above are measured with no load, with the tire mounted on an applicable rim and filled with a specified internal pressure, unless otherwise specified.
"Applicable rim" means a standard rim ("Measuring Rim" in ETRTO STANDARDS MANUAL, "Design Rim" in TRA YEAR BOOK) defined in the following standards according to the tire size, and "specified internal pressure" means In the following standards, it means the air pressure specified corresponding to the maximum load capacity, and the "maximum load capacity" means the maximum mass allowed to be loaded on the tire according to the following standards. The standard is an industrial standard that is effective in regions where tires are produced and used, and refers to JATMA YEAR BOOK in Japan, ETRTO STANDARDS MANUAL in Europe, and TRA YEAR BOOK in the US.

According to the present invention, it is possible to provide a pneumatic tire that suppresses radiated sound and has improved noise performance.

1 is a sectional view of a pneumatic tire according to an embodiment of the present invention in a tire width direction. It is a plane explanatory view showing the belt structure of the pneumatic tire of Drawing 1. It is a schematic explanatory drawing which shows typically the vibrating shape of the tread surface in the tire for general passenger cars. It is explanatory drawing which shows typically the vibrating shape of the tread surface in the pneumatic tire of FIG. It is a plane explanatory view showing the belt structure of the pneumatic tire concerning other embodiments of this invention.

Hereinafter, an embodiment for carrying out the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, a pneumatic tire (hereinafter, also simply referred to as “tire”) 10 according to an embodiment of the present invention includes a carcass 12 that extends in a toroidal shape between a pair of bead portions 11, and a carcass. The crown belt 12 includes a tilted belt 13 arranged on the outer side in the tire radial direction and a tread 14 arranged on the outer side in the tire radial direction of the tilted belt 13. The pneumatic tire 10 is used by being mounted on an automobile, and is particularly suitable as a pneumatic tire for passenger cars.
The pneumatic tire 10 may be provided with a circumferential cord layer disposed on the tire radial direction outer side of the crown portion of the carcass 12. In the present embodiment, one circumferential cord layer 15 is provided, and the inclined belt is provided. The belt 16 is composed of 13 and the circumferential cord layer 15. The circumferential code layer 15 may be arranged inside or outside the inclined belt 13 in the tire radial direction.

The inclined belt 13 has a cord that inclines with respect to the tire circumferential direction, and is disposed through the tire equator CL and has a wide inclined belt layer having at least a relatively wide width in the tire width direction, and a tire width direction. It consists of two layers, a narrow-width slanted belt layer having a relatively narrow width. Here, it is preferable that at least the tire width direction center of the wide inclination belt layer and the tire equator CL are aligned. In the present embodiment, the inclined belt 13 has only two layers, the wide inclined belt layer 13a and the narrow inclined belt layer 13b, and the tire width direction center of the wide inclined belt layer 13a and the tire equator CL coincide with each other. ..
The width of the widest widest tilted belt layer (the widest tilted belt layer 13a in the present embodiment) of the tilted belt 13 is 90% to 115%, preferably 90% to 115% of the tire width direction width (tread width) of the tread 16. It is set to 100% to 105% (105% in this embodiment).

The cord of the inclined belt 13 can be a metal cord, particularly a steel cord, but can also be an organic fiber cord (in the present embodiment, a steel cord). The steel cord is mainly composed of steel and may contain various trace contents such as carbon, manganese, silicon, phosphorus, sulfur, copper and chromium. In addition, a monofilament cord or a cord obtained by twisting a plurality of filaments can be used, and various designs can be adopted for the twist structure, and the cross-sectional structure, twist pitch, twist direction, and distance between adjacent filaments can be varied. Things can be used. Further, a cord obtained by twisting filaments of different materials can be adopted, and the cross-sectional structure is not particularly limited, and various twist structures such as single twist, layer twist, and double twist can be adopted.

The inclination direction of the cord of the inclination belt 13 with respect to the tire circumferential direction may be the same or different between the wide inclination belt layer and the narrow inclination belt layer (in the present embodiment, the inclination directions are different, see FIG. 2 ).
The number of driving is, for example, in the range of 20 to 60 pieces/50 mm, but is not limited to this range, and the wide tilt belt layer and the narrow tilt belt layer may be the same or different. good.

In the pneumatic tire 10, the width of the wide inclined belt layer (in the present embodiment, the wide inclined belt layer 13a) in the tire width direction is W1, and the narrow inclined belt layer (in the present embodiment, the narrow inclined belt layer 13b). ) Is W2, the tire width direction width of the wide inclination belt layer is W2, and the tire width direction end of the narrow inclination belt layer (the width inclination of one of the wide inclination belt layers is closer to the tire width direction end). In the tire width direction distance to the tire width direction end of the belt layer, when the longer one is D1 and the shorter one is D2, W2/W1=0.2 to 0.7, and D1/D2=2. .0 to 8.0, preferably W2/W1=0.4 to 0.6, and D1/D2=4.0 to 6.0, so that the wide sloped belt layer and the narrow sloped belt layer. Are formed.

In the present embodiment, the narrow width slant belt layer 13b of the slant belt 13 has a tire width direction width of 0.5 times the tire width direction width W1 of the wide width slant belt layer 13a that is also the tire width direction maximum width of the slant belt 13. Have Further, the widths of both shoulder regions of the wide-width inclined belt layer 13a located on both sides in the tire width direction are different from each other in the tire width direction, and the width of one shoulder region in the tire width direction is the width of the other shoulder region in the tire width direction. The width is 2.0 times, that is, D1/D2=2.0 in this embodiment.
That is, in the pneumatic tire 10, at least the narrow-width inclined belt layer (in the present embodiment, the narrow-width inclined belt layer 13b) is asymmetric in the pair of tire half portions sandwiching the tire equator CL in the tire width direction. It is located in.

As described above, from the tire width direction end of the wide slope belt layer to the tire width direction end of the narrow slope belt layer (the tire of the narrow slope belt layer, which is closer to the tire width direction end of each wide slope belt layer). The width in the width direction is made different, that is, by making the low-rigidity region different in the tire width direction width, it becomes possible to separate the vibrations into different modes, so that the peak level of the sound is reduced. Especially it can be lowered.

If the width of the inclined belt layer in the tire width direction is wider than the width of the narrow belt layer of the inclined belt 13 in the tire width direction, the width of the low rigidity region is too wide, and the amplitude of the vibration mode itself is small. Since the effect of suppressing the radiated sound is difficult to obtain, the tire width direction width of the wide inclined belt layer, that is, the tire width direction width W1 of the wide inclined belt layer 13a and the narrow inclined belt layer in the present embodiment. The width in the tire width direction, that is, in the embodiment, in the width W2 in the tire width direction of the narrow inclined belt layer 13b, it is necessary that W2/W1≧0.2. On the other hand, when the width of the wide-width inclined belt layer in the tire width direction is narrow, the vibration modes cannot be sufficiently separated, and a large amplitude is likely to be generated in the end, so that W2/W1≦0.7 is required. is there.

Further, the width in the tire width direction of the low rigidity region (the region in which only the wide inclined belt layer does not overlap the wide inclined belt layer and the narrow inclined belt layer) is narrow on both sides in the tire width direction (the width in the tire width direction is narrow and the width in the wide tire is narrow). However, if the difference in width in the tire width direction is too large, a large amplitude will occur in the wide belt layer. As a result, the reduction rate of noise is reduced. Therefore, the distance from the tire width direction end of the wide slope belt layer (in the present embodiment, the wide slope belt layer 13a) to the tire width direction end of the narrow slope belt layer (in the present embodiment, the narrow slope belt layer 13b). When the longer one of the (shoulder regions) is D1 and the shorter one is D2, it is necessary to satisfy D1/D2≧2.0 and D1/D2≦8.0.

Generally, in many passenger car tires in which the cord of the inclined belt layer has a large inclination angle with respect to the tire circumferential direction, in a high frequency range of 400 Hz to 2 kHz, the tread is subjected to vibration modes such as primary, secondary, and tertiary vibrations in the cross-sectional direction. Since the surface has a shape that uniformly vibrates greatly (shown by a chain double-dashed line in FIG. 3), a large radiated sound is generated. Therefore, when the inclined belt layer is configured to include a wide inclined belt layer having a relatively wide width in the tire width direction and a relatively narrow inclined belt layer having a relatively narrow width in the tire width, the widthwise central portion of the tread is less likely to spread in the tire radial direction. , The spread of the tread surface in the circumferential direction (amplitude of vibration) is suppressed (shown by the broken line in FIG. 3), so that the radiated sound is reduced. Note that FIG. 3 shows a schematic configuration of the tire.

In the pneumatic tire 10, the narrow width inclined belt layer (in the present embodiment, the narrow width inclined belt layer 13b) serving as the center region of the inclination belt 13 is replaced with the wide inclination belt layer (in the present embodiment, the wide inclination belt layer 13a). ) In the tire width direction in the range of 0.2 times to 0.7 times the width W1 in the tire width direction, the narrow width inclined belt layer (in the present embodiment, the narrow width inclined belt layer 13b). And the tire width direction width of the shoulder region of the wide inclined belt layer (in the present embodiment, the wide inclined belt layer 13a) that does not overlap with the tire radial direction, the longer distance D1 is 2.0, which is the shorter distance D2. It is configured to be different within the range of not less than double and not more than 8.0. Therefore, the vibration mode is separated into two vibration modes (shown by a broken line and a chain line in FIG. 4). As a result, the peak level of the sound is lowered more effectively, so that the radiated sound generated from the tire can be further reduced.

As described above, in the pneumatic tire 10 that reduces the amplitude itself of the vibration generated in the tire and reduces the peak level of the sound by separating the vibration into different modes, other tire configurations, for example, the inclination belt layer It is possible to reduce the sound emitted from the tire regardless of the size of the cord angle.
Here, in the pneumatic tire 10, the tilted belt 13 includes at least two tilted belt layers (in this embodiment, the wide tilted belt layer 13a and the narrow width tilted belt layer 13b) having mutually different widths in the tire width direction. In addition, the cord forming the wide inclined belt layer 13a has an inclination angle θ1 with respect to the tire circumferential direction of 30° to 85° (30°≦θ1≦85°), and the cord forming the narrow inclined belt layer 13b inclines with respect to the tire circumferential direction. It is preferable that the angle θ2 is 10° to 30° (10°≦θ2≦30°) and θ1>θ2 is satisfied.

When the inclination angle θ1 of the cord forming the wide-width inclined belt layer 13a with respect to the tire circumferential direction is set to 30° or more, the rubber stretches in the circumferential direction when the tread surface of the tread 16 is deformed, so that the contact length of the tire is sufficient. Secured in. As a result, cornering power can be increased and high turning performance can be realized. If the inclination angle θ1 exceeds 85°, the bending rigidity in the circumferential direction may be excessively reduced, so the inclination angle θ1 is set to 85° or less.
However, when the inclination angle θ1 of the cord of the widest inclined belt layer 13a is increased in this way, the vibration mode of the tire changes, so that radiated sound is generated and noise performance tends to deteriorate. More specifically, most of the tires in which the cord of the inclined belt layer inclines at an angle of approximately 30° or more and 85° or less with respect to the tire circumferential direction, in the high frequency region of 400 Hz to 2 kHz, the In the second and third vibration modes, the tread surface uniformly vibrates greatly, which may cause a large radiated sound.

Therefore, if the inclination angle θ2 of the cord of the narrow width inclined belt layer 13b with respect to the tire circumferential direction is set to be smaller than the inclination angle θ1 of the cord of the wide inclination belt layer 13a and is in the range of 10° or more and 30° or less. Since the out-of-plane bending rigidity in the tire circumferential direction is appropriately maintained near the tire equator CL, it is possible to suppress vibration of the tread surface due to the above vibration mode. That is, the spread of the tread 16 in the tire circumferential direction in the vicinity of the tire equator CL is suppressed, and as a result, the radiated sound can be further reduced.

By setting the inclination angle θ2 to 10° or more, the out-of-plane bending rigidity in the tire circumferential direction can be maintained without impairing the action of ensuring the ground contact length in the wide inclination belt layer 13a, and the inclination angle θ2 can be reduced. By setting the angle to 30° or less, the out-of-plane bending rigidity in the tire circumferential direction in the vicinity of the tire equator CL is sufficiently maintained, so that the generation of radiated sound can be more reliably reduced.
When the pneumatic tire 10 is mounted on a vehicle, one of the tire width direction distances D1 and D2 on which D2 is located is located on the inner side in the vehicle mounting direction, that is, FIGS. In the example of 5, it is preferable to specify the vehicle mounting direction so that the left side in the drawing is located inside the vehicle mounting direction. By being mounted in this manner, a lateral force is generated from the pair of tires inward in the vehicle mounting direction, and steering stability (toe-in effect) when traveling straight ahead is improved.

Further, in the present embodiment, the circumferential cord layer 14 has cords extending along the tire circumferential direction, and only one layer is provided outside the inclined belt 13 in the tire radial direction. The circumferential code layer 14 is not limited to one layer, and two or more layers may be provided, or the circumferential code layer 14 may not be provided.
The circumferential cord layer 14 preferably has a high rigidity, and more specifically, it is made of a rubberized layer of a cord extending in the tire circumferential direction, and the Young's modulus of the cord is Y (GPa) and the driving number is n( It is preferable that 1500≧X≧750, where X=Y×n×m, where the circumferential code layer 14 is m layers.

The tire width direction end portion of the circumferential direction cord layer 14 is positioned outside the tire width direction end portion of the narrow width inclined belt layer 13b in the width direction and inside the tire width direction end portion of the wide width inclined belt layer 13a. Preferably.
A wavy cord may be used for the circumferential cord layer 14 in order to increase the breaking strength. Similarly, in order to increase the breaking strength, a high elongation cord (e.g., elongation at break of 4.5 to 5.5%) may be used. As the cord material, various materials can be adopted, and typical examples thereof include rayon, nylon, polyethylene naphthalate (PEN), polyethylene terephthalate (PET), aramid, glass fiber, carbon fiber, steel and the like. Can be adopted. From the viewpoint of weight reduction, the organic fiber cord is particularly preferable.

As this cord, a monofilament cord, a cord formed by twisting a plurality of filaments, or a hybrid cord formed by twisting filaments made of different materials can be used. The number of driving is set in the range of 20 to 60 pieces/50 mm, but is not limited to this range.

The circumferential code layer 14 may be designed to have a width in the tire width direction wider or narrower than that of the inclined belt 13. For example, the maximum width inclined belt layer (in the present embodiment, the largest width in the tire width direction of the inclined belt 13). , 90 to 110% of the width of the wide inclined belt layer 13a).
Further, it is particularly advantageous from the viewpoint of manufacturing that the circumferential direction code layer 14 is configured as a spiral layer, but a plurality of core wires arranged in parallel to each other in a plane are wrapping wires while maintaining the parallel arrangement. The strip-shaped cords bundled by the above may be wound in a spiral shape.

The pattern of the tread 14 may be either a symmetrical pattern in the tire width direction with the tire equator CL sandwiched or an asymmetrical pattern. The negative rate of the pattern can be, for example, 30% or less. When the circumferential main groove is provided on the tread 14, the number of the circumferential main grooves is preferably about 2 to 4, and the groove width of the circumferential main groove is preferably about 4 to 10 mm. The circumferential main groove may not be provided, and the rib-shaped land portion or the block-shaped land portion may be used.
The tread rubber forming the tread 14 may be formed by a CAP/BASE structure having a plurality of rubber layers of different types in the tire radial direction. As the plurality of rubber layers, those having different tangent loss, modulus, hardness, glass transition temperature, material and the like can be used. Further, the ratio of the thickness in the tire radial direction of the plurality of rubber layers may be changed in the tire width direction, and only the circumferential groove bottom or the like may be a rubber layer different from the periphery thereof.

Further, the tread rubber may be formed by a divided tread structure including a plurality of rubber layers of different types in the tire width direction. As the plurality of rubber layers, those having different tangent loss, modulus, hardness, glass transition temperature, material and the like can be used. Further, the ratio of the length in the tire width direction of the plurality of rubber layers may be changed in the tire radial direction, and only in the vicinity of the circumferential groove, only near the tread end, only the shoulder land portion, only the center land portion, etc. Alternatively, only a limited part of the area may be a rubber layer different from the surrounding area.

For the carcass line, which is the extending wheel portion of the carcass 12 in the tire width direction cross section, various structures in a pneumatic tire can be adopted. For example, the carcass maximum width position in the tire radial direction is set to the bead portion side. It can be brought closer to the tread side. As an example, the carcass maximum width position can be provided outside the bead base portion in the tire radial direction in a range of 50% to 90% with respect to the tire height. The number of carcass cords to be driven can also adopt various structures in a pneumatic tire, and for example, a range of 20 to 60 cords/50 mm is preferable, but the number is not limited to this range. The cord arrangement of the carcass may be either a bias structure or a radial structure (a radial structure is adopted in this embodiment), and the material of the carcass cord is preferably organic fiber.

The carcass folded-back portion in which the carcass 12 folded back the bead core of the bead portion 11 can also adopt various structures in the pneumatic tire, for example, the folded-back end of the carcass should be located inward of the bead filler end in the tire radial direction. It is also possible to extend the carcass folded end to the outside of the bead filler end or the tire maximum width position in the tire radial direction, and in some cases, to extend to the inside of the belt in the tire width direction from the tire width direction end. Further, when the carcass 12 is composed of a plurality of carcass layers, the positions of the carcass turn-up ends in the tire radial direction can be different. Further, it is also possible to adopt a structure in which a plurality of bead core members are sandwiched or a structure in which the carcass is wrapped around a bead core, without the carcass folded-back portion.

In the tire side portion, the maximum tire width position can be provided in the range of 50% to 90% in terms of tire height, outside the bead base portion in the tire radial direction, and can also have a structure having a rim guard. ..
Alternatively, the structure may be such that no bead filler is provided.
The bead core can adopt various structures in a pneumatic tire, such as a circular shape and a polygonal shape, and as described above, in addition to the structure in which the carcass is wound around the bead core, the bead core is divided and the carcass is divided into a plurality of bead core members. It is also possible to have a structure that sandwiches. Further, in order to reinforce the periphery of the bead core, a rubber layer, a cord layer or the like may be further provided on the bead portion for the purpose of reinforcement or the like. Such an additional member can be provided at various positions with respect to the carcass and the bead filler.

The rubber composition constituting the inner liner arranged on the inner surface of the tire has an air permeability coefficient of 1.0×10 ⁻¹⁴ cc·cm/(cm ² ·s·cmHg) or more and 6.5×10 ⁻¹⁰ cc·cm. /(Cm ² ·s·cmHg) or less, and for example, a rubber layer mainly containing butyl rubber is preferable. In addition to the rubber layer containing butyl rubber as a main component, a film layer containing resin as a main component may be used.
In addition, a porous member (sponge, etc.) may be disposed on the inner surface of the tire to reduce cavity resonance noise, or electrostatic flocking may be performed, and a sealant for preventing air leakage during tire puncture. A member can also be provided.
Further, the pneumatic tire may be a side-reinforced run-flat tire having a crescent-shaped reinforcing rubber on the tire side portion.

In the pneumatic tire 10 of the present embodiment, at least the narrow width inclined belt layer (in the present embodiment, the narrow width inclined belt layer 13b) is asymmetric in the pair of tire half portions sandwiching the tire equator CL in the tire width direction. However, the configuration other than the inclined belt 13 can also be asymmetrical. Examples of the asymmetrical structure include a bead filler, a carcass folded end portion, and a tire side portion outer shape.

As shown in FIG. 5, a pneumatic tire 20 according to another embodiment of the present invention includes a wide tilt belt layer (in the present embodiment, a wide tilt belt layer 13a) and a narrow tilt belt layer (in the present embodiment, The cord extending direction of the narrow inclined belt layer 13b) is formed so as to be in the same inclined direction with respect to the tire equator CL. Other configurations are similar to those of the pneumatic tire 10 described above. Since the cord extending directions of the wide slope belt layer and the narrow slope belt layer are in the same slope direction with respect to the tire equator CL, the shearing force acting between the slope belt layers is reduced and the rolling resistance is particularly improved. You can

10, 20: Pneumatic tire, 11: Bead part, 12: Carcass, 13: Tilt belt, 13a: Wide tilt belt layer, 13b: Narrow tilt belt layer, 14: Tread, 15: Circumferential direction cord layer, 16: Belt, CL: Tire equator

Claims (6)

A slanted belt comprising at least two slanted belt layers each having a carcass that extends in a toroidal shape between a pair of bead portions, and a cord that is disposed on a tire radial direction outer side of a crown portion of the carcass and that slants with respect to the tire circumferential direction And a tread arranged on the tire radial direction outer side of the inclined belt layer, which is a pneumatic tire comprising:
The inclined belt is disposed through the tire equator, at least, the tire width direction width is composed of a relatively wide narrow belt layer and a relatively narrow narrow belt layer,
The entire narrow slope belt layer is between the tire width direction ends of the wide slope belt layer,
The tire width direction width of the wide width inclined belt layer is W1, the tire width direction width of the narrow width inclined belt layer is W2, and the tire width direction end of the wide width inclined belt layer to the tire width direction end of the narrow width inclined belt layer. Of the tire width direction distances, when the longer one is D1 and the shorter one is D2,
W2/W1=0.2 to 0.7, and D1/D2=2.0 to 8.0
A pneumatic tire characterized by: When the inclination angle of the cord of the wide inclined belt layer with respect to the tire circumferential direction is θ1, and the inclination angle of the cord of the narrow inclined belt layer with respect to the tire circumferential direction is θ2,
30°≦θ1≦85°, 10°≦θ2≦30°, and θ1>θ2
The pneumatic tire according to claim 1, wherein The pneumatic tire according to claim 1 or 2, wherein the vehicle mounting direction is specified such that the side, on which D2 is located, of the tire width direction distances D1 and D2 is located inside the vehicle mounting direction. On the tire radial direction outer side of the inclined belt, a circumferential cord layer made of a rubberized layer of a cord extending along the tire circumferential direction is provided,
When the Young's modulus of the cords of the circumferential direction code layer is Y (GPa), the number of driving is n (pieces/50 mm), and the number of layers of the circumferential direction code layer is m, X=Y×n×m is defined. ,
1500≧X≧750
The pneumatic tire according to claim 1, wherein the pneumatic tire is The pneumatic tire according to claim 4, wherein the number of hammered-in cords in the circumferential cord layer is 20 to 60 cords/50 mm. The pneumatic tire according to claim 4 or 5, wherein a width of the circumferential cord layer in the tire width direction is 90 to 110% of a width of the wide inclined belt layer in the tire width direction.

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